1. Field of the Invention
The present invention relates to a cornea surgical operation apparatus for incising the cornea of a patient's eye into a layer when a cornea surgical operation for correcting refraction is performed.
2. Description of Related Art
In recent years, a cornea surgical operation for correcting refraction referred to as a Laser in Situ Keratomileusis (LASIK) operation has received widespread attention. In this operation, after a flap is formed by incising a cornea of 150 .mu.m thick from the epithelium of the cornea to the stroma of the cornea into a layer with one end of the cornea left as a hinge, the stroma of the cornea is ablated by the amount of corrective refraction with excimer laser and then the flap is restored. In this surgical operation, a cornea surgical operation apparatus referred to as a Microkeratome is used.
As the Microkeratome, an apparatus has been known that the cornea protruded from the opening of a suction part attracted by suction and attached to the peripheral part of the cornea (from the limbus of the cornea to a conjunctiva) is pressed flat by a cornea pressing member and then that the cornea is incised into a layer in a nearly uniform thickness by straight moving a blade (cutting edge) in the direction of a hinge while it is being vibrated transversely. It is because there is a limit to the formation of the sharp angle of the cutting edge of the blade itself, and because the considerable hard Bowman membrane (under the epithelium of the cornea) is hard to incise only by the straight movement of the blade.
However, when the blade is vibrated transversely for incising, since a speed in transverse direction becomes zero at the limit point of movement in the transverse vibration and a speed in the straight movement is constant, the force for cutting the cornea is reduced to the minimum at the point A as shown in FIG. 7, which results in producing a defect that the cut cross section of the cornea is made nonuniform.